Implement sendfile on FreeBSD and Darwin

1 files changed, 189 insertions, 2 deletions

diff --git a/src/sys/sendfile.rs b/src/sys/sendfile.rs
index 7f7a7751..1190518d 100644
--- a/src/sys/sendfile.rs
+++ b/src/sys/sendfile.rs
@@ -6,8 +6,195 @@ use libc::{self, off_t};
 use Result;
 use errno::Errno;
 
-pub fn sendfile(out_fd: RawFd, in_fd: RawFd, offset: Option<&mut off_t>, count: usize) -> Result<usize> {
-    let offset = offset.map(|offset| offset as *mut _).unwrap_or(ptr::null_mut());
+/// Copy up to `count` bytes to `out_fd` from `in_fd` starting at `offset`.
+///
+/// Returns a `Result` with the number of bytes written.
+///
+/// If `offset` is `None`, `sendfile` will begin reading at the current offset of `in_fd`and will
+/// update the offset of `in_fd`. If `offset` is `Some`, `sendfile` will begin at the specified
+/// offset and will not update the offset of `in_fd`. Instead, it will mutate `offset` to point to
+/// the byte after the last byte copied.
+///
+/// `in_fd` must support `mmap`-like operations and therefore cannot be a socket.
+///
+/// For more information, see [the sendfile(2) man page.](http://man7.org/linux/man-pages/man2/sendfile.2.html)
+#[cfg(any(target_os = "android", target_os = "linux"))]
+pub fn sendfile(
+    out_fd: RawFd,
+    in_fd: RawFd,
+    offset: Option<&mut off_t>,
+    count: usize,
+) -> Result<usize> {
+    let offset = offset
+        .map(|offset| offset as *mut _)
+        .unwrap_or(ptr::null_mut());
     let ret = unsafe { libc::sendfile(out_fd, in_fd, offset, count) };
     Errno::result(ret).map(|r| r as usize)
 }
+
+cfg_if! {
+    if #[cfg(any(target_os = "freebsd",
+                 target_os = "ios",
+                 target_os = "macos"))] {
+        use sys::uio::IoVec;
+
+        #[allow(missing_debug_implementations)]
+        struct SendfileHeaderTrailer<'a>(
+            libc::sf_hdtr,
+            Option<Vec<IoVec<&'a [u8]>>>,
+            Option<Vec<IoVec<&'a [u8]>>>,
+        );
+
+        impl<'a> SendfileHeaderTrailer<'a> {
+            fn new(
+                headers: Option<&'a [&'a [u8]]>,
+                trailers: Option<&'a [&'a [u8]]>
+            ) -> SendfileHeaderTrailer<'a> {
+                let header_iovecs: Option<Vec<IoVec<&[u8]>>> =
+                    headers.map(|s| s.iter().map(|b| IoVec::from_slice(b)).collect());
+                let trailer_iovecs: Option<Vec<IoVec<&[u8]>>> =
+                    trailers.map(|s| s.iter().map(|b| IoVec::from_slice(b)).collect());
+                SendfileHeaderTrailer(
+                    libc::sf_hdtr {
+                        headers: {
+                            header_iovecs
+                                .as_ref()
+                                .map_or(ptr::null(), |v| v.as_ptr()) as *mut libc::iovec
+                        },
+                        hdr_cnt: header_iovecs.as_ref().map(|v| v.len()).unwrap_or(0) as i32,
+                        trailers: {
+                            trailer_iovecs
+                                .as_ref()
+                                .map_or(ptr::null(), |v| v.as_ptr()) as *mut libc::iovec
+                        },
+                        trl_cnt: trailer_iovecs.as_ref().map(|v| v.len()).unwrap_or(0) as i32
+                    },
+                    header_iovecs,
+                    trailer_iovecs,
+                )
+            }
+        }
+    }
+}
+
+cfg_if! {
+    if #[cfg(target_os = "freebsd")] {
+        use libc::c_int;
+
+        libc_bitflags!{
+            /// Configuration options for [`sendfile`.](fn.sendfile.html)
+            pub struct SfFlags: c_int {
+                /// Causes `sendfile` to return EBUSY instead of blocking when attempting to read a
+                /// busy page.
+                SF_NODISKIO;
+                /// Causes `sendfile` to sleep until the network stack releases its reference to the
+                /// VM pages read. When `sendfile` returns, the data is not guaranteed to have been
+                /// sent, but it is safe to modify the file.
+                SF_SYNC;
+                /// Causes `sendfile` to cache exactly the number of pages specified in the
+                /// `readahead` parameter, disabling caching heuristics.
+                SF_USER_READAHEAD;
+                /// Causes `sendfile` not to cache the data read.
+                SF_NOCACHE;
+            }
+        }
+
+        /// Read up to `count` bytes from `in_fd` starting at `offset` and write to `out_sock`.
+        ///
+        /// Returns a `Result` and a count of bytes written. Bytes written may be non-zero even if
+        /// an error occurs.
+        ///
+        /// `in_fd` must describe a regular file or shared memory object. `out_sock` must describe a
+        /// stream socket.
+        ///
+        /// If `offset` falls past the end of the file, the function returns success and zero bytes
+        /// written.
+        ///
+        /// If `count` is `None` or 0, bytes will be read from `in_fd` until reaching the end of
+        /// file (EOF).
+        ///
+        /// `headers` and `trailers` specify optional slices of byte slices to be sent before and
+        /// after the data read from `in_fd`, respectively. The length of headers and trailers sent
+        /// is included in the returned count of bytes written. The values of `offset` and `count`
+        /// do not apply to headers or trailers.
+        ///
+        /// `readahead` specifies the minimum number of pages to cache in memory ahead of the page
+        /// currently being sent.
+        ///
+        /// For more information, see
+        /// [the sendfile(2) man page.](https://www.freebsd.org/cgi/man.cgi?query=sendfile&sektion=2)
+        pub fn sendfile(
+            in_fd: RawFd,
+            out_sock: RawFd,
+            offset: off_t,
+            count: Option<usize>,
+            headers: Option<&[&[u8]]>,
+            trailers: Option<&[&[u8]]>,
+            flags: SfFlags,
+            readahead: u16
+        ) -> (Result<()>, off_t) {
+            // Readahead goes in upper 16 bits
+            // Flags goes in lower 16 bits
+            // see `man 2 sendfile`
+            let flags: u32 = ((readahead as u32) << 16) | (flags.bits() as u32);
+            let mut bytes_sent: off_t = 0;
+            let hdtr = headers.or(trailers).map(|_| SendfileHeaderTrailer::new(headers, trailers));
+            let hdtr_ptr = hdtr.as_ref().map_or(ptr::null(), |s| &s.0 as *const libc::sf_hdtr);
+            let return_code = unsafe {
+                libc::sendfile(in_fd,
+                               out_sock,
+                               offset,
+                               count.unwrap_or(0),
+                               hdtr_ptr as *mut libc::sf_hdtr,
+                               &mut bytes_sent as *mut off_t,
+                               flags as c_int)
+            };
+            (Errno::result(return_code).and(Ok(())), bytes_sent)
+        }
+    } else if #[cfg(any(target_os = "ios", target_os = "macos"))] {
+        /// Read bytes from `in_fd` starting at `offset` and write up to `count` bytes to
+        /// `out_sock`.
+        ///
+        /// Returns a `Result` and a count of bytes written. Bytes written may be non-zero even if
+        /// an error occurs.
+        ///
+        /// `in_fd` must describe a regular file. `out_sock` must describe a stream socket.
+        ///
+        /// If `offset` falls past the end of the file, the function returns success and zero bytes
+        /// written.
+        ///
+        /// If `count` is `None` or 0, bytes will be read from `in_fd` until reaching the end of
+        /// file (EOF).
+        ///
+        /// `hdtr` specifies an optional list of headers and trailers to be sent before and after
+        /// the data read from `in_fd`, respectively. The length of headers and trailers sent is
+        /// included in the returned count of bytes written. If any headers are specified and
+        /// `count` is non-zero, the length of the headers will be counted in the limit of total
+        /// bytes sent. Trailers do not count toward the limit of bytes sent and will always be sent
+        /// regardless. The value of `offset` does not affect headers or trailers.
+        ///
+        /// For more information, see
+        /// [the sendfile(2) man page.](https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPages/man2/sendfile.2.html)
+        pub fn sendfile(
+            in_fd: RawFd,
+            out_sock: RawFd,
+            offset: off_t,
+            count: Option<off_t>,
+            headers: Option<&[&[u8]]>,
+            trailers: Option<&[&[u8]]>
+        ) -> (Result<()>, off_t) {
+            let mut len = count.unwrap_or(0);
+            let hdtr = headers.or(trailers).map(|_| SendfileHeaderTrailer::new(headers, trailers));
+            let hdtr_ptr = hdtr.as_ref().map_or(ptr::null(), |s| &s.0 as *const libc::sf_hdtr);
+            let return_code = unsafe {
+                libc::sendfile(in_fd,
+                               out_sock,
+                               offset,
+                               &mut len as *mut off_t,
+                               hdtr_ptr as *mut libc::sf_hdtr,
+                               0)
+            };
+            (Errno::result(return_code).and(Ok(())), len)
+        }
+    }
+}